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Congestion Status Precondition for SIP

Congestion Status Precondition for SIP. draft-alexander-congestion-status-preconditions-00.txt. Corey Alexander (coreya@nortel.com) John Rutledge (jrutledg@nortel.com). MMUSIC, 63 th IETF, August 1 st , 2005. Introduction. Goal: Congestion-based Admission Control

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Congestion Status Precondition for SIP

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  1. Congestion Status Precondition for SIP draft-alexander-congestion-status-preconditions-00.txt Corey Alexander (coreya@nortel.com) John Rutledge (jrutledg@nortel.com) MMUSIC, 63th IETF, August 1st, 2005

  2. Introduction • Goal: Congestion-based Admission Control • Congestion Status Precondition – “cong” – proposes to delay session establishment until a determination of the congestion level in the network can be made • Utilizes two other drafts to delay session establishment until the status of congestion in the network is determined: • draft-babiarz-tsvwg-rtecn-04.txt: Real-time ECN draft defines new semantics for the Explicit Congestion Notification (ECN) bits in the IP header for real-time inelastic flows • draft-alexander-rtp-payload-for-ecn-probing-01.txt: Defines an RTP payload format for ECN probing Congestion Status Precondition for SIP MMUSIC, 63th IETF, Paris, France

  3. Background • Real-time ECN draft defines new semantics for ECN marking in the context of real-time inelastic flows • Defines two levels of congestion • RTP payload format for ECN probing defines new RTP payload • Dynamically selected RTP payload type value • Fields in payload used for detection of devices not conformant to Real-time ECN draft • Admission control achieved by using stream of probe packets prior to session establishment to detect presence of congestion in network • Use case outlining use of Real-time ECN and RTP payload format for ECN for admission control is available • draft-alexander-rtecn-use-cases-00.txt Congestion Status Precondition for SIP MMUSIC, 63th IETF, Paris, France

  4. Congestion Status Precondition • Example m=audio 50002 RTP/AVP 0 8 18 c=IN IP4 192.168.1.200 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:18 G729/8000 a=curr:cong e2e none a=des:cong mandatory e2e sendrecv 104 • Note 1: No rtpmap attribute for probe format • Note 2: 104 value in desired-status line Congestion Status Precondition for SIP MMUSIC, 63th IETF, Paris, France

  5. Congestion Status Precondition • Note 1: Congestion Status Precondition tied to use of probe format • view preconditions as applying to allrtpmap attributes for a media type • specification of probe “media” in rtpmap attribute redundant • Note 2: Selection of dynamic payload type for probe format in new parameter additional-data, consisting of new type payload-type for Congestion Status precondition desired-status = "a=des" precondition-type SP strength-tag SP status-type SP direction-tag SP additional-data precondition-type = "cong" | "qos" | token additional-data = "" | payload-type payload-type = 96-127 Congestion Status Precondition for SIP MMUSIC, 63th IETF, Paris, France

  6. Next Steps • Feedback • additional-data parameter • Precondition tied to use of RTP payload format for ECN • Other comments • Q&A • List Discussion Congestion Status Precondition for SIP MMUSIC, 63th IETF, Paris, France

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